The present invention relates to an apparatus for removing foreign matters from condenser cooling water and, more particularly, to an apparatus for removing foreign matters such as marine creatures from sea water which is taken as cooling water for cooling condenser, by effectively separating discharging such foreign matters by means of flow of water.
Power plants such as steam power plants or nuclear power plants which make use of sea water as the condenser cooling water usually have screens or the like disposed at the sea water intake to arrest and remove foreign matters from the sea water flowing into the condenser. The screen, however, cannot arrest tiny foreign matters such as larval forms of creatures and shellfishes. These larval forms attach to the wall of the sea water intake pipe and grow to form a heavy deposit. The creatures then die to come off from the pipe wall and the mass of dead creatures flow into the condenser to cause problems such as clogging of the cooling water tubes in the condenser. Hitherto, there has been no means for avoiding such a problem.
In recent years, there is an increasing demand for an apparatus which can remove the dead creatures or like foreign matters from the sea water before the same enters the condenser.
To cope with this demand, an apparatus as shown in FIG. 1 has been proposed in which the foreign matters are caught by a filter surface provided in a foreign matters removal apparatus 4 in the water inlet system 2 of the condenser 1 and are suitably discharged from the discharge system 5. In order to effectively catch such large foreign matters as cannot pass through the condenser cooling water pipe and to smoothly discharge the thus caught foreign matters, in the known foreign matter removing apparatus of the type mentioned above, the water inlet system is connected tangentially to the foreign matters removing apparatus so as to impart a swirling flow along the filter surface. It has been proposed also to wash and clean the filter surface by swirling flow or reverse swirling flow which takes place in accordance with the opening degree of a valve such as butterfly valve directly connected to the inlet system.
In general, however, it is required to minimize the rate of discharge from the discharging system 5 in relation to the rate of intake of water from the inlet system 2', in order to maintain a sufficiently large rate of water supply to the condenser. Therefore, when a swirling flow along the filter surface is generated for cleaning the filter surface, the flow velocity becomes higher at the portion of the filter surface adjacent to the outlet system 2 as indicated by an arrow A than at other portions of the same. In consequence, even though the swirling flow is formed, the foreign matters are concentrated to the portion of the filter surface adjacent to the outlet system 2 to cause a heavy clogging in that portion of the filter surface.
In consequence, the effective passage area of the filter is decreased to deteriorate the performance for removing the foreign matters. In addition, the flowing velocity of the sea water through the filter is increased to promote the tendency of clogging to further impair the performance of the foreign matter removing apparatus and to increase the loss of energy or pressure drop in the cooling water circulating system.